Image forming apparatus including control system provided with a master control unit and a plurality of subsidiary control units

Abstract

In an image forming apparatus of the type including a plurality of functional modules each having particular functions proper to the unit, a control system having a master control unit and a plurality of subsidiary control units respectively in control of the individual functional modules wherein each of the plurality of subsidiary control units operates principally under the control of the master control unit through a communication network of the common interface bus type but is operable independently of the master control unit when required or preferred by the subsidiary control unit per se. At least one of the functional modules is provided with a standard mode of operation and a local mode of operation. The standard and local modes are incompatible with one another.

What is claimed is: 
     
       1. An image forming apparatus having at least one functional module and a control system comprising a) first control means in control of said functional module, and   b) second control means capable of communicating with the first control means, said second control means being operative to control the first control means by communicating with the first control means to supervise the operation of the image forming apparatus,   c) said functional module having a standard mode of operation in which the functional module operates under the control of said first control means operating under the control of the second control means and a local mode of operation in which the functional module operates under the control of said first control means, said standard mode and said local mode being concurrently incompatible with each other in said functional module.   
     
     
       2. An image forming apparatus as set forth in claim 1, further comprising d) failure detecting means for detecting a failure invited in the image forming apparatus and supplying failure detect information indicative of the occurrence of said failure to said second control means so that said second control means means controls said first control means to incorporate the functional mode into the standard mode.   
     
     
       3. An image forming apparatus as set forth in claim 1, in which said first control means is enabled to select said local mode in said functional module by permission of said second control means. 
     
     
       4. An image forming apparatus including first and second functional modules and a control system comprising a) first and second subsidiary control means in control of said first and second functional modules, respectively, and   b) single master control means which may be coupled to each of said first and second subsidiary control means for being in control of each of the first and second subsidiary control means,   c) said first functional module having a standard mode of operation in which the functional module operates under the control of said first subsidiary control means operating under the control of said master control means,   d) said second functional module having a standard mode of operation in which the functional module operates under the control of said second subsidiary control means operating under the control of said master control means and a local mode of operation in which the functional module operates under the control of said second subsidiary control means operating independently of said master control means, the local mode of said second functional module being concurrently incompatible with the standard mode of each of the first and second functional modules.   
     
     
       5. An image forming apparatus as set forth in claim 4, further comprising d) failure detecting means for detecting a failure invited in the image forming apparatus and supplying failure detect information indicative of the occurrence of said failure to said master control means and enabling said second functional module to operate exclusively in said standard mode in the presence of the failure detect information transferred from said master control means to said second subsidiary control means.   
     
     
       6. An image forming as set forth in claim 4, in which said second subsidiary is enabled to select said local mode in said second functional module by permission of said master control means. 
     
     
       7. An image forming apparatus having at least one functional module and a control system comprising first control means in control of said functional module and second control means capable of communicating with the first control means, wherein said functional module has a standard mode of operation in which the functional module operates under the control of said first control means and a local mode of operation in which the functional module operates under the control of said second control means, said standard mode of operation and said local mode of operation being concurrently incompatible with each other in said functional module. 
     
     
       8. An image forming apparatus including first and second functional modules and a control system comprising first and second subsidiary control means in control of said first and second functional modules, respectively, and single master control means which may be coupled to each of said first and second subsidiary control means for being in control of each of the first and second subsidiary control means, wherein said first functional module has a standard mode of operation in which the functional module operates under the control of said first subsidiary control means operating under the control of said master control means and said second functional module has a standard mode of operation in which the functional module operates under the control of said second subsidiary control means operating under the control of said master control means and a local mode of operation in which the functional module operates under the control of said second subsidiary control means operating independently of said master control means, the local mode of operation of said second functional module being concurrently incompatible with the standard mode of operation of each of the first and second functional modules. 
     
     
       9. An image forming apparatus having at least one functional module and a control system comprising a) first control means in control of said functional module,   b) second control means capable of communicating with the first control means,   c) said functional module having a standard mode of operation in which the functional module operates under the control of said first control means and a local mode of operation in which the functional module operates under the control of said second control means, said standard mode of operation and said local mode of operation being concurrently incompatible with each other in said functional module, and   d) failure detecting means for detecting a failure invited in the image forming apparatus and supplying failure detect information indicative of the occurrence of said failure to said second control means and enabling said functional module to operate exclusively in said standard mode of operation in the presence of the failure detect information transferred from said second control means to said first control means.   
     
     
       10. An image forming apparatus including first and second functional modules and a control system comprising a) first and second subsidiary control means in control of said first and second functional modules, respectively,   b) single master control means which may be coupled to each of said first and second subsidiary control means for being in control of each of the first and second subsidiary control means,   c) said first functional module having a standard mode of operation in which the functional module operates under the control of said first subsidiary control means operating under the control of said master control means,   d) said second functional module having a standard mode of operation in which the functional module operates under the control of said second subsidiary control means operating under the control of said master control means and a local mode of operation in which the functional module operates under the control of said second subsidiary control means operating independently of said master control means, the local mode of operation of said second functional module being concurrently incompatible with the standard mode of operation of each of the first and second functional modules, and   e) failure detecting means for detecting a failure invited in the image forming apparatus and supplying failure detect information indicative of the occurrence of said failure to said master control means and enabling said second functional module to operate exclusively in said standard mode of operation in the presence of the failure detect information transferred from said master control means to said second subsidiary control means.   
     
     
       11. An image forming apparatus having at least one functional module and a control system comprising first control means in control of said functional module and second control means capable of communicating with the first control means, wherein said functional module has a standard mode of operation in which the functional module operates under the control of said first control means and a local mode of operation in which the functional module operates under the control of said second control means, said standard mode of operation and said local mode of operation being concurrently incompatible with each other in said functional module, and wherein said first control means is enabled to select said local mode of operation in said functional module by permission of said second control means. 
     
     
       12. An image forming apparatus including first and second functional modules and a control system comprising a) first and second subsidiary control means in control of said first and second functional modules, respectively,   b) single master control means which may be coupled to each of said first and second subsidiary control means for being in control of each of the first and second subsidiary control means,   c) said first functional module having a standard mode of operation in which the functional module operates under the control of said first subsidiary control means operating under the control of said master control means,   d) said second functional module having a standard mode of operation in which the functional module operates under the control of said second subsidiary control means operating under the control of said master control means and a local mode of operation in which the functional module operates under the control of said second subsidiary control means operating independently of said master control means, the local mode of operation of said second functional module being concurrently incompatible with the standard mode of operation of each of the first and second functional modules,   e) said second subsidiary control means being enabled to select said local mode of operation in said second functional module by permission of said master control means.   
     
     
       13. An image forming apparatus including first and second functional modules and a control system comprising (a) first and second subsidiary control means in control of said first and second functional modules, respectively,   (b) single master control means which may be coupled to each of said first and second subsidiary control means for being in control of each of the first and second subsidiary control means,   (c) first coupling means for coupling said first subsidiary control means to said master control means for allowing the master control means and first subsidiary control means to communicate at any time with each other through said first coupling means,   (d) second coupling means for coupling said second subsidiary control means to said master control means for allowing the master control means and the second subsidiary control means to periodically communicate with each other through said second coupling means,   (e) said first functional module having a standard mode of operation in which the functional module operates under the control of said first subsidiary control means operating under the control of said master control means and a local mode of operation in which the functional module operates under the control of said first subsidiary control means operating independently of said master control means,   (f) said second functional modules having a standard mode of operation in which the functional module operates under the control of said second subsidiary control means operating under the control of said master control means   (g) the local mode of operation of said first functional module being concurrently incompatible with the standard mode of operation of each of the first and second functional modules.   
     
     
       14. An image forming apparatus as set forth in claim 13, in which said control system further comprises failure detecting means for detecting a failure invited in the image forming apparatus and supplying failure detect information indicative of the occurrence of said failure to said master control means and enabling said first functional module to operate exclusively in said standard mode in the presence of the failure detect information transferred from said master control means to said first subsidiary control means. 
     
     
       15. An image forming apparatus as set forth in claim 13, in which said first subsidiary control means is enabled to select said local mode in said first functional module by permission of said master control means.